Revisiting supernova constraints on a light CP-even scalar. (arXiv:2005.00490v3 [hep-ph] UPDATED)
<a href="http://arxiv.org/find/hep-ph/1/au:+Dev_P/0/1/0/all/0/1">P. S. Bhupal Dev</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Mohapatra_R/0/1/0/all/0/1">Rabindra N. Mohapatra</a>, <a href="http://arxiv.org/find/hep-ph/1/au:+Zhang_Y/0/1/0/all/0/1">Yongchao Zhang</a>
A light CP-even Standard Model (SM) gauge-singlet scalar $S$ can be produced
abundantly in the supernova core, via the nucleon bremsstrahlung process $N N
to N N S$, due to its mixing with the SM Higgs boson. Including the effective
$S$ coupling to both nucleons and the pion mediators, we evaluate the
production amplitude for the $S$ particle and point out a key difference with
the well-known light CP-odd scalar (axion) and vector boson (dark photon)
cases. Taking the subsequent decay and re-absorption of $S$ into account, we
present a complete calculation of the energy loss rate for the $S$ particle. We
then use the SN1987A luminosity constraints to derive updated supernova limits
on the mixing of the scalar $S$ with the SM Higgs boson. We find that the
mixing angle $sintheta$ with the SM Higgs is excluded only in the narrow
range of $3.9 times 10^{-7}$ to $7.0 times 10^{-6}$, depending on the scalar
mass up to about 147 MeV, beyond which the supernova limit disappears.
A light CP-even Standard Model (SM) gauge-singlet scalar $S$ can be produced
abundantly in the supernova core, via the nucleon bremsstrahlung process $N N
to N N S$, due to its mixing with the SM Higgs boson. Including the effective
$S$ coupling to both nucleons and the pion mediators, we evaluate the
production amplitude for the $S$ particle and point out a key difference with
the well-known light CP-odd scalar (axion) and vector boson (dark photon)
cases. Taking the subsequent decay and re-absorption of $S$ into account, we
present a complete calculation of the energy loss rate for the $S$ particle. We
then use the SN1987A luminosity constraints to derive updated supernova limits
on the mixing of the scalar $S$ with the SM Higgs boson. We find that the
mixing angle $sintheta$ with the SM Higgs is excluded only in the narrow
range of $3.9 times 10^{-7}$ to $7.0 times 10^{-6}$, depending on the scalar
mass up to about 147 MeV, beyond which the supernova limit disappears.
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